Means for bending the rolls of rolling machines



Aug. 4, 1959 u. G. SHAPIRO ETAL 2,397,538

MEANS FOR'BENDING THE ROLLS 0F ROLLING MACHINES Filed Nov. 12, 1957 4Sheets-Sheet 1 F d. L8

1959 u. G. SHAPIRO ETAL 2,897,538

MEANS FOR BENDINC THE ROLLS OF ROLLING MACHINES Filed NOV. 12, 1957 4Sheets-Sheet 2 4, 1959 u. G. SHAPIRO ETAL' 2,

MEANS FOR BENDING THE ROLLS OF ROLLING MACHINES Filed Nov. 12, 1957 V 4Sheets-Sheet s u. G. SHAPIRO ET AL 2,897,538

Aug. 4, 1959 MEANS FOR BENDINC- THE ROLLS OF ROLLING MACHINES Filed Nov.12, 1957 v 4 Sheets-Sheet 4 DEANS FOR BENDlNG THE ROLLS OF ROLLING MAC*l l' Uriel G. Shapiro and Thomas S. Rochester, both ofWallsend-on-Tyne, England, assignors to Commercial Plastics Limited,Wallsend-on-Tyne, England, a British company Application November 12,B57, Serial No. 695,808

Claims priority, application Great Britain November 15, 1956 5 Claims.(Cl. 18-2) This invention relates to means for bending the rolls ofrolling machines or mills employed for the rolling of material which isfed between two or more rolls, said bending being for the purpose ofcompensating for or correcting the deflection of one or more of therolls, which may take place during the rolling operation, in orderthereby to obtain a uniform thickness of the rolled film or sheet ofmaterial.

While the invention is particularly suitable for use with rolls employedfor the calendering of plastic films or sheets, it is also applicable torolls used in the rolling of metals and other materials, or in therolling or grinding of chocolate, pigments and the like, where thematerial to be rolled is fed in the form of a viscous paste or the likebetween pairs of rolls.

It is well-known that during the rolling or calendering of plasticmaterial, for example, forces develop which cause the rolls to bend,these forces depending on the size of the bank of excess feed materialformed adjacent the gap between the rolls, as well as on the speed ofrolling, and on the viscosity of the material at the workingtemperature. Such bending during rolling would, unless compensated for,cause the rolled film or sheet to be of non-uniform thickness, beingthicker at the middle of the rolls.

One known method of compensating for roll bending during rolling hasbeen to employ crowned rolls, the initial degree of crowning being suchthat during the Working operation the crowning adjacent the roll gap iseliminated, giving a uniform size of rolling gap and consequentlyuniform thickness of the rolled material. This compensating methodinvolves very accurate machining of the rolls, and a given degree ofcrowning will only be suitable for a given set of operating conditions,and in order to conform to another set of conditions where the bendingforces are different, the rolls have to be changed for rolls ofdifferent crowning, or different machines have to be used.

To obviate these disadvantages of compensating for bending merely bycrowning the rolls, one or both cooperating rolls have been extendedoutwards of their main bearings and hydraulic pressure has been appliedto auxiliary floating hearings on their ends, in a vertical direction,in order to bend the rolls to any desired degree of initial camber or torestore the rolls to parallel relation after bending due to operationalpressures. The application of bending pressure to the ends of the rolls,however, involves utilising the main bearings as fulcra, therebyimposing increased loading and strain on those bearings, tending toshorten their effective life. Also, if the bending force is appliedupwardly to a lower roll mounted in floating main bearings, the rollwill be pushed up as soon as this force slightly exceeds the downwardsforces acting on the roll, and there is consequently a danger of foulingwith an upper roll. Moreover, before this condition is reached theupward force will tend to reduce the stability, within the bearings, ofthe journals Patented Aug. 4, 1959 of the roll to which the said forceis applied, with the possibility of variations in the thickness of thesheet resulting. On the other hand, if the bending force is appliedvertically downwards, the usual jacks which sup port and verticallyadjust the main bearings of at least the lower roll, must overcome muchgreater forces when closing the gap between the rolls, so that largermotors and reduction gears are needed to operate the jacks.

The object of the present invention is to provide an improved method ofand means for applying a compensating bending to a rolling-machine roll,either initially or after deflection during the rolling operation,whereby the disadvantages attending bending by vertical pressuresapplied to the ends of a roll, as explained above, are avoided, theinvention enabling bending to be elfected without imposing anyadditional load on the main bearings or on the adjusting jacks, orcausing instability of the roll journals.

According to the invention, in a rolling machine means are provided forapplying to each end of one of the rolls a turning couple acting in aplane containing the axis of said roll and the axis of a co-operatingadjacent roll so as to tend to bend said first roll about its middle andthereby compensate for or correct for deflection caused during therolling operation, said turning means being independent of the mainbearings of the roll.

The turning means may comprise auxiliary free or floating bearingsindependent of the main bearings and encircling opposite end portions ofa roll, and means for imparting to said auxiliary bearings an angularturning eifort or couple acting in a plane which contains the axis ofthe roll and the axis of the adjacent co-operating roll so as to applyto each end portion of said first roll a turning couple or torque actingin said plane and tending to bend the roll about its middle.Conveniently, the auxiliary bearings each carries a lever member or armrigid therewith, and means are provided for moving the two lever membersor arms towards or away from one another in a common plane to bend theroll. The means for angularly moving the lever members or arms mayconsist of hydraulic means, such as a hydraulic cylinder carried by eachlever member or arm and provided with piston means co-operating withstationary abutment surfaces. The two cylinders of the respective leverarms are arranged to be interconnected to ensure balanced hydraulicforces and therefore the elimination of unbalanced axial forces on theroll bearings.

In the accompanying drawings,

Figure 1 is a diagrammatic front view of a rolling machine fitted withroll bending means in accordance with the present invention.

Figure 2 is a diagrammatic side view of the machine shown in Figure 1.

Figure 3 is a more detail part sectional view of one end of a roll andassociated bending means in accordance with the invention.

Figure 4 is an end elevation of the roll end of Figure 3.

Figure 5 is a horizontal section on line V--V, Figure 4.

Figure 6 is a schematic diagram showing the general layout of ahydraulic system suitable for operating the roll bending means.

Referring now to the drawings, the rolling machine illustrated thereinmay be used for calendering or rolling plastic material into sheets orfilms, and comprises a desired number of co-operating horizontal rolls,indicated by the reference numerals 1, 2, 3 and 4, which may be eitherslightly crowned or parallel-sided, between successive pairs of whichhot plastic is fed and rolled out, the gaps between such successivepairs being progressively reduced and the final pair of rolls 3, 4,having a gap suitable for giving to the finished rolled sheet or filmthe thickness required. As shown in Figures 1 and 2,

the upper pair of rolls 1, 2, are placed side by side whilst the restare disposed vertically one above the other giving aninvertedL-formation, but, if desired, the rolls may be all vertically stacked orotherwise disposed, as in a Z-formation for example.

Each roll, such as 4, has journal extensions 5, 6, at opposite ends andthe journals are supported in main bearings 7 which are adjustablymounted in the sides of a stationary frame 8 so that the gaps betweensuccessive pairs of rolls can be adjusted as may be desired to give thedesired thickness gauge to the material which is being rolled betweenthem. In the case of the rolls 2, 3, and 4, which are in verticalalignment, the main bearings 7 are freely mounted for verticaldisplacement in the sides of the frame 8 under the control of a pressurescrew 9 or equivalent means acting downwards on the top roll 2 and ascrew or jack 10 supporting the lower roll 4, with compression springs11, 12, between intermediate rolls and their adjacent rolls.

During the rolling of the plastic materials between some or all of theseveral pairs of adjacent rolls, at least one roll will have its axisslightly deflected or bowed, resulting in the thickness of the sheet orfilm being thicker at the middle than at the ends unless means areprovided for compensating for or correcting such deflection, as iscontemplated by the present invention.

Thus, in accordance with the invention, the apparatus includes new andimproved means whereby one or more of the rolls (in the caseillustrated, the lower roll 4) may be adjustably bent byexternally-applied forces, independently of the bending by the materialduring rollto both pistons and to ensure balanced hydraulic forces andthe elimination of unbalanced axial forces on the main roll bearings 7.

By moving the bearing-carried arms either towards one another or awayfrom one another the initiallycambered roll 4 may thus be given either amore positive camber, causing its middle portion to approach thecooperating roll 3 and its axis to bend upwards fromits normal straightcondition; or a negative camber, causing its middle portion to recedefrom the co-operating roll 3, and its axis to bend downwards of itsnormal straight condition. Such deflections of the roll axis areindicated in exaggerated form by the broken lines in Figure 1. Anegative camber would be given, relatively to the original degree ofcrowning of its surface if, for example, the initial cambering is suchthat for rolling a given thickness of sheet, no bending would berequired, and it is then required to roll a sheet of greater thickness.If a thinner sheet is required, a positive camber would be given by thebending operation, it being understood that thinner gauges of materialgive a greater bending pressure.

ing, in order to compensate for such bending by the material. Thus,mounted on each projecting end of the journal extensions 5 and 6 of thelower roll 4 is a free or floating auxiliary bearing 13, conveniently ofa tworow tapered roller type, which is surrounded by an outer housing 14having attached to it, or integral with, a radial arm 15 which dependsvertically. The lower end of this arm 15 is arranged to have a forceapplied to it, in a plane containing the axis of the roll 4, tending toturn it angularly in one direction or the other in the said planecontaining the axis of the roll. Such force is applied simultaneously tothe two arms 15 at opposite ends of the roll 4 but in oppositedirections, so that the arms 15 are moved either away from one anotheror towards one another. The result of so moving the arms 15 angularly ina plane containing the axis of the roll 4 is that a couple or turningtorque acting in said plane is applied to the end journals 5 and 6 ofthe roll 2 through the auxiliary bearings 13 so that the roll becomesbent in arcuate form about its middle point without imposing anyadditional load upon the main bearings 7.

The forces on the lever arms 15 tending to turn them angularly, in onedirection or the other, may be applied by means of a horizontalhydraulic cylinder 16 attached to or incorporated in the lower end ofeach arm 15 and containing a double-acting stationary piston 17 to oneside or the other of which hydraulic pressure can be applied. The piston17 carries two central stems or rods 18 and 19 extending through theends of the cylinder 16, the extremities of said stems 18, 19, engagingtwo spaced-apart vertical abutment surfaces 20, 21, between which thelower end of the arm 15 is free to move or float up and down as the armis deflected or as the roll 4 is adjusted vertically to vary the rollinggap. When hydraulic pressure is applied, to one side or to the other ofthe stationary piston 1'7, the reaction of the stem 18 or 19 on one orother of the abutment surfaces 20 and 21 will cause the cylinder 16, andthus the arm 15, to move relatively in one angular direction or theother. Preferably the hydraulic supply lines to the cylinders 16 of thetwo lever arms 15 are interconnected both as regards the inner ends onone side of the pistons 17 as well as the outer ends on the other sideof the pistons 17, to enable hydraulic power to be appliedsimultaneously Referring now to Figures 3 to S of the drawings whichillustrate one constructional arrangement in greater detail, the mainbearing 7 which supports the one journal extension 5 of the roll 4 isshown as comprising a plain bush 23 which is so dimensioned as to have asmall radial clearance 24 so as to permit of a small degree of angularmovement of the roll 4 during the bending operation. Other types ofbearing, however, such as self-aligning bearings, for example, may beemployed if desired. 7 V

Mounted on the journal extension 5 outwardly of the said main bearing 7is the floating auxiliary bearing 13 which is of a two-row taperedroller type comprising pairs of conical inner and outer race rings, 25and 26 respectively, separated by spacing members 27 and 27 and two rowsof tapered rollers, 28 and 29, running between the respective conicalrace surfaces of the inner and outer race rings 25, 26, with theirlarger ends directed outwardly.

The inner race rings 25 of the auxiliary bearing 13 are mounted upon asleeve 30 which is fixed upon the journal extension 5, being locatedagainst an abutment shoulder 31 at the inner end and being held in placeat the outer end by a driving pinion or spacing sleeve 32 which issecured by an end plate 33 bolted to the end of the shaft.

The outer race rings 26 of the auxiliary bearing 13 are contained withinthe outer housing 14 which carries a lower web of flange 34- bolted tothe arm 15 so that the latter depends vertically therefrom. The arm 15carries at its lower end an extension member 35 which is formed with asemi-circular recess 36 extending transversely across one face, withinwhich recess is interlockingly housed the horizontal hydraulic cylinder16 which is retained in place by an outer semi-circular clamping coveredplate 37 secured by bolts 38. The ends of the cylinder 16 are closed byend caps 39 provided With central apertures 40 through which pass thestems or rods 18 and 19 of the doubleacting piston 17 which is containedwithin the cylinder 16 as herein before described, and parts (not shown)are provided in the cylinder walls on either side of the said piston 17for the entry and exit of a hydraulic fluid.

The outer extremities of the piston stems 18 and 19 which engage the twospaced apart abutment surfaces 20, 21, are preferably formed withrounded end surfaces 41, 42, as shown, and the overall length betweenthe two extreme end surfaces 41 and 42 is only slightly less than thedistance between the abutment surfaces 20, 21, so that the piston 17remains virtually stationary as far as movement in an axial direction isconcerned.

The two abutment surfaces 20 and 21 are formed by small plates 43 and 44which are secured to parallel It will be understood that when the twoarms 15 are simultaneously moved towards or away from one another thecouple tending to bend the roll into arcuate form is applied to thejournal extensions 5 and 6 by virtue of the upper rollers of theauxiliary bearing 13 being caused to exert a downward force on thejournal at one point thereon, whilst the lower rollers of the bearing 13are caused to exert an upward force on the journal at a point which islongitudinally displaced from the point of application of thefirst-named force.

To prevent angular movement of each arm 15 in a direction transverse tothe axis of the roll 4, the extension member 35 at the lower end of thesaid arm is provided with laterally projecting side arms 49, d9, whichslidingly engage within guide slots 50, 59, formed in plates 51, 51,secured to the walls 45 and 46 of the bracket member 47.

The source of power for operating the hydraulic cylinders 16 andeffecting the bending of the roll 4 is conveniently a compressed airoperated hydraulic pump 52 which is shown in Figure 6 as being connectedto the cylinders through a changeover 4-way valve 53 enabling thepressure to be applied either to the inner ends or to the outer ends ofthe cylinders, the opposite ends in each case being connected toexhaust. The hydraulic fluid is contained in a reservoir 54 and thereference numeral 55 denotes an accumulator bottle for stabilizing thepressure and preventing sudden fluctuations. Various pressure gauges areshown in the circuit being denoted generally by the reference letter G.

In a modification, instead of each lever arm 15 carrying a hydrauliccylinder fitted with a stationary piston, a single stationary cylindermay be provided midway between the two arms 15 and fitted with twospaced movable pistons respectively coupled to the arms, fluid pressurebeing admitted either to the outer ends of the pistons or to the spacebetween the pistons according to whether the arms are to be movedtowards or away from one another.

It is to be understood that the bending may be applied to the roll orrolls either initially, before the material is operated upon, or afterrolling of the material has commenced, when the roll has been deflectedby the material, in which case the bending is applied to bend the rollto a condition in which the gap is of uniform size throughout the lengthof the rolls during the rolling operation.

The bending may be applied to any one or more of the rolls as may bedesired, and the rolls may initially have parallel sides, instead ofbeing crowned.

We claim:

1. A rolling machine comprising a frame; at least two cooperating rollseach mounted in bearings in opposite sides of the frame one of saidrolls being extended at each end beyond the frame; auxiliary freebearing units inde pendent of the frame bearings and encircling theextended ends of said roll; a lever arm rigid with each auxiliarybearing unit; and means for acting on the two lever arms to move themangularly relatively to one another in a plane which contains the axesof said roll and of an adjacent roll, so as to bend the said roll aboutits middle.

2. A rolling machine comprising a frame; at least two cooperating rollseach mounted in bearings in opposite sides of the frame, one of saidrolls being extended at each end beyond the frame; auxiliary freebearing units independent of the frame bearings and encircling theextended ends of said roll; a lever arm rigid with each auxiliarybearing unit; a hydraulic cylinder carried by each lever arm; a pistonwithin the cylinder; stationary abutment means co-operating with eachpiston to prevent axial movement thereof; and means for supplying fluidpressure to said cylinders to cause the lever arms to move angularlyrelatively to one another in a plane which contains the axes of saidroll and of an adjacent roll so as to bend said roll about its middle.

3. A rolling machine according to claim 2, wherein each piston carriesaxial stems at opposite sides, said stems extending through the ends ofthe cylinder, and the abutment means for each piston are provided withvertical abutment surfaces engaged by the ends of the piston stems, saidabutment surfaces permitting the piston to move vertically between themfor the adjustment of the rolls of the machine.

4. A rolling machine comprising a frame; at least two cooperating rollseach mounted in bearings in the frame, one of said rolls being extendedbeyond the frame; an auxiliary free bearing unit encircling eachextended end of said roll, said bearing unit having two laterally-spacedrows of rolling elements enclosed within a housing; a lever arm rigidlycarried by each said bearing housing; and means for acting on the twolever arms to move them angularly relatively to one another in a planewhich contains the axes of said roll and of an adjacent roll, in orderto bend said roll about its middle.

5. A rolling machine comprising a frame; at least two co-operating rollsmounted in bearings in the frame; two auxiliary free bearing units,independent of the frame bearings, encircling the respective ends of oneof the rolls; a lever aim rigid with each auxiliary bearing unit; meansfor acting on the two lever arms to move them angularly relatively toone another in a plane which con tains the axes of said roll and of anadjacent roll, so as to bend the said roll about its middle; and meansfor preventing said lever arms from turning angularly about the axis ofthe roll.

References Cited in the file of this patent UNITED STATES PATENTS2,611,150 Goulding Sept. 23, 1952 FOREIGN PATENTS 747,347 Great BritainApr. 4, 1956

